U.S. Pat. No. 7,735,188B discloses a blower vacuum having an air inlet cover and a blower tube both of which attach to a blower housing for operation of the blower vacuum in a blower mode. The air inlet cover may removably attach to both the blower housing and to the blower tube. The air inlet cover and the blower tube have a protrusion which is inserted through a hole in the housing when attached to the housing. The protrusion abuts a button when the air inlet or the blower tube are attached to the housing. When the button is depressed by the protrusion, a switch is closed in an electrical circuit and this permits operation of the electric motor. The switch is arranged in series with a user operated switch.
This means that the impeller, which is driven by the motor, is operable when the button is depressed by the protrusion and the user operated switch is actuated. In this way the user cannot put his hand in near the impeller and accidentally activate the impeller because the air inlet cover or blower tube must be correctly attached to the housing in order for the protrusion to depress the button and start the motor.
However when the attachment is removed the button is exposed via a hole in the housing. This means that there can still be some circumstances whereby the impeller can be operated when the blower tube or the air inlet grill are removed and the impeller is exposed. For example, the button can be depressed if a screwdriver or a similarly shaped object is inserted into the hole. This means that the user could still activate the impeller when their hand is in the vicinity of the exposed impeller.